1) Field of the Invention
This invention relates in general to process for the conversion of normorphinone and its derivatives, which can be synthesized from morphine, to the corresponding 14-hydroxynormorphinone and its derivatives including oxycodone, oxymorphone, noroxymorphone, and naltrexone. Noroxymorphone is a key intermediate for the production of important narcotic analgesics and antagonists. In another aspect, the invention is directed to certain novel intermediates.
2) Background Art
14-Hydroxy-substituted morphine derivatives are important narcotic analgesics and/or antagonists. These drugs include oxycodone, oxymorphone, nalbuphine, naloxone, naltrexone, and nalmefene. They are readily synthesized from thebaine, which is a minor component of gum opium. As the supply of thebaine is limited and the demand is increasing, therefore, the price of thebaine is high. As a result, many alternative approaches have been made for the preparation of 14-hydroxymorphine derivatives.
The reported efforts for preparing these narcotics bearing a 14-hydroxy group from readily abundant starting materials morphine or codeine (a minor component of gum opium, which may also be synthesized by methylation of morphine) are summarized as the following: (1) the conversion of codeine to thebaine through dihydrocodeinone (5.4% yield, H. Rapoport, et al., J. Am. Chem. Soc., vol. 89, 1967, p. 1942 and H. Rapoport, et al., J. Org. Chem., vol. 15, 1950, p. 1103), codeinone (20% yield, I. Seki, Chem. Pharm. Bull., vol. 18, 1970, p. 671 and H. Rapoport, et al., J. Am. Chem. Soc., vol. 77, 1955, p. 490) or 6-methyl ether of codeine (using manganese dioxide, 67% yield, R. B. Barber, et al., J. Med. Chem., vol. 18, 1975, p. 1074); (2) the oxidation of codeinone pyrrolidinyl di-enamine to 14-hydroxycodeinone (30-40% yield, I. Seki, Chem. Pharm. Bull., vol. 18, 1970, p. 671); (3) the direct allylic oxidation of codeine to the corresponding 14-hydroxy derivatives with manganese dioxide (I. Brown, et al., J. Chem. Soc., 1960, p. 4139), and selenium dioxide plus t-butyl hydrogen peroxide (M. A. Schwartz, et al., J. Med. Chem., vol. 24, 1981, p. 1525); and (4) the six-step transformation of codeine to noroxycodone (52% yield) and noroxymorphone (43% yield) using photochemically generated singlet oxygen (M. A. Schwartz, et al., J. Med. Chem. vol. 24, 1981, p. 1525); and (5) the preparation of noroxymorphone from morphine through an intermediate with carbamate protection on the nitrogen atom (17-position) or a carbonate protecton at the 3 position and the carbamate protection at the 17 position of normorphinone dienol acetate with MCPBA in the substantial absence of water (37% yield, Wallace, U.S. Pat. No. 5,112,975). These processes suffer from either low yields, long steps, not amenable to scale-up, or involve the use of environmentally unfriendly heavy metals.
It is therefore an object of the present invention to provide methods for the conversion of normorphinone and its derivatives to the corresponding 14-hydroxynormorphinone and its derivatives. A further object of the invention is to provide processes which provide relatively high yields of the desired products. Another object is to provide methods which are environmentally safe and avoid the use of heavy metals.
Another object of the present invention is to provide processes which can use morphine or codeine as starting material instead of the scarce thebaine. Codeine is a component of gum opium and can also be produced by methylation of morphine using known prior art techniques. A still further object of the present invention is to provide the use of an aqueous system in the oxidation step to form 14-hydroxynormorphinone which is not only environmentally friendly, but also desirable in which to conduct the subsequent hydrogenation reaction without the need for isolating the 14-hydroxynormorphinone intermediate. A still further object is to provide certain intermediates which are novel compositions. It is a further object of this invention to provide intermediates for specific products, such as oxycodone, oxymorphone, naltrexone and noroxymorphone. These and other objects will readily become apparent to those skilled in the art in light of the teachings herein disclosed.